(1) Field of Technology
The present invention relates generally to ratchet pulley devices for tightening cords or ropes, and more particularly to a thumb-drive for facilitating the movement of loose rope through the device.
(2) Description of the Related Art
Rope winches are generally known in the art. See, for example, FIG. 1, showing a winch described in U.S. Pat. No. 5,722,640, the entire contents of which are hereby incorporated by reference. As seen in FIG. 1, winch 2 includes a rotatably mounted lever 4. The rotation of lever 4 tightens rope 6, which pulls object 10 in the general direction of winch 2. Lever 4 provides a mechanical advantage needed in many instances to move large loads.
In contrast to rope winches, which are designed to move objects, ratchet pulley devices for tightening cords and ropes are structurally configured for securing objects in a desired location. FIGS. 2 and 3 show an example of a device 30 described in U.S. Pat. No. 5,368,281, the entire contents of which are hereby incorporated by reference. Referring primarily to the exploded view provided in FIG. 3, device 30 includes sheave 32, which may be made of sheave-halves 32A and 32B. Sheave 32 is rotatably mounted within housing 34. Ratchet mechanism 36 has tooth 36A that is biased by spring 40 to engage sprocket 32C of sheave 32. Housing 34 also defines channel 34A, which helps guide rope around sheave 32.
Referring primarily to FIG. 2, sheave 32 engages rope 42, which has a tag-end 42A and a main body 42B that is securable to an object, e.g., a canoe on top of a car (not shown). The opposite end of housing 32 is connected to hook 46, which is securable to a stable object, e.g., flange 48. The object to be secured (not shown) is quickly and easily secured by pulling on tag-end 42A of rope 42, which ratchetably tightens the main body 42B of rope 42, thereby preventing backwards slip of rope 42.
With conventional ratchet pulley devices, it is common to provide an opening 44 in housing 34 through which sheave 32 is accessible. Opening 44 can be used to manually rotate sheave 32, which may be needed, depending on the stiffness or type of rope used, to load rope into the sheave. While generally adequate for loading most ropes, applicant has found that accessing sheave 32 by opening 44 to load ropes is relatively time consuming due to the structurally-constrained length of opening 44, which allows for only a partial-rotation of the sheave. Using the conventional ratchet pulley device, numerous (e.g., 5-10) partial-rotations of the sheave may be required to load the rope around the sheave into operable position. When using a single ratcheting pulley device, this large number of partial-rotations is undesirable. When using a large number of ratcheting pulley devices, both the number of partial-rotations required to load the rope, and the undesirability, are amplified.
The present invention addresses these and other problems by providing a structural solution that allows for quick and easy loading of the rope onto the sheave with a single movement of the thumb.